The invention relates to the field of integrated optics, and in particular to a spatial diversity scheme particularly suitable for a hitless switch for integrated optics.
A distinct advantage of Integrated Optical Circuit (IOC) devices is that they are suitable for direct coupling to optical fibers since the guided light wave is well confined in both transverse dimensions. An electro-optic directional coupler switch comprises two parallel strip line waveguides forming a passive directional coupler with an electro-optic pad at the edge of each waveguide. Initially, light is focused onto one of the waveguides and the amount of light coupled to the adjacent channel can be controlled electro-optically. This scheme not only permits direct amplitude modulation of the light propagating in one channel, but allows light to be switched from one channel to another.
Wavelength-division-multiplexed (WDM) optical transmission systems carry multiple wavelength channels simultaneously on a single guiding optical line. Dynamic reconfiguration of functional optical components that operate on a subset of the used WDM spectrum may be employed to reroute one or more WDM signals around a broken link in the network, to add/drop one or more wavelength channels at a network node, or to perform other signal processing operations on a wavelength-selective basis. It is preferable that during the dynamic reconfiguration of such optical components, which operate on a subset of the WDM spectrum, the data flow on other wavelength channels not be interrupted or deteriorated during the reconfiguration operation. This is referred to as hitless switching or hitless reconfiguration of the optical component.